Search Google Appliance

Measuring & Mapping

Where, how far, and how much? People have invented an astonishing array of devices to answer seemingly simple questions like these. Measuring and mapping objects in the Museum's collections include the instruments of the famous—Thomas Jefferson's thermometer and a pocket compass used by Meriwether Lewis and William Clark on their expedition across the American West. A timing device was part of the pioneering motion studies of Eadweard Muybridge in the late 1800s. Time measurement is represented in clocks from simple sundials to precise chronometers for mapping, surveying, and finding longitude. Everyday objects tell part of the story, too, from tape measures and electrical meters to more than 300 scales to measure food and drink. Maps of many kinds fill out the collections, from railroad surveys to star charts.

This instrument is a specialized timekeeper for finding longitude at sea. Thomas Earnshaw made this chronometer in England about 1798. It became part of the James Arthur Collection at New York University, and the university donated a portion of the collection, including this chronometer, to the Smithsonian in 1984.

To find longitude at sea, a chronometer was set to the time of a place of known longitude, like Greenwich, England. That time, carried to a remote location, could be compared to local time. Because one hour of difference in time equals 15 degrees difference in longitude, the difference in time between the chronometer and local time would yield local longitude. The instruments require careful handling to keep precise time. Although the original box for this instrument has not survived, most chronometers are fitted in a wooden box in a gimbal to remain level and compensate for the movement of a ship at sea.

Thomas Earnshaw (1749-1829) was a pioneer in chronometer development. He is credited with introducing to chronometer design two important features that became standard parts of the timekeeper in the 19th century—the detached detent escapement and, independently of his rival John Arnold, the bimetallic compensation balance. His simplifications permitted others to undertake batch production of chronometers, and his work received an award of £2500 from Britain’s Longitude Board in 1805.

This octant has a rosewood frame, flat brass index arm, and ivory name plate. The ivory scale is graduated every 20 minutes from -5° to +95° and read by vernier to single minutes of arc. The "Andw Newell Maker Boston" inscription refers to Andrew Newell (1751-1798), a mathematical instrument maker in Boston. Inside the box is the trade card of David Baker, proprietor of a nautical instrument shop in New Bedford during the second quarter of the nineteenth century.

This is a complex brass instrument, consisting of a nocturnal, a sundial, a lunar aspectarium, and a geometrical quadrant. The maker, Caspar Vopel (1511-1561), taught mathematics in Cologne and studied cosmography. He made a number of armillary spheres and globes.

The nocturnal is used to find the time of night from observations of circumpolar stars. On a simple nocturnal, a pair of circular scales and an alidade are mounted together. The larger circle is divided into a monthly zodiac calendar to set the instrument to the proper date. The smaller circle is divided into 24 hours, eighteen of which are marked to be read by touch in the dark. The observer would sight the pole star through the center of the instrument and align the alidade with the "pointer" stars of Ursa Major. Simple nocturnals were one of the most commonplace mathematical instruments in the sixteenth and seventeenth centuries.

This compendium’s nocturnal and lunar aspectarium are on one side with the sundial in the design of fifteenth century astronomer Regiomontanus and the geometrical quadrant on the other. The nocturnal side has a zodiac calendar on the outermost ring of the base plate. The calendar scale is marked with the names of the months in Latin, divided to 10 and subdivided to 1 day numbered by 10. The zodiac scale has the names and engraved representations of the constellations, and each sign has a scale 0 to 30 degrees, divided to 10, subdivided to 1, numbered by 10. There are two moving volvelle plates, which are used to find the time of the rising and setting of the sun. The first has a pointer, marked "INDEX SOLIS" and with a sun symbol extending across the zodiac calendar carries scales for the time and the age of the moon. The time scale has hours 1 to 12 twice, divided to 1, subdivided to 15 minutes, numbered by 1 hour, and each hour position has a point for counting in the dark (except one 12, which has the index arm). Asterisks are engraved on the points for 6, the other 12, and 6. The lunar scale runs from 0 to 29|1/2|, divided to 1, subdivided to |1/4|, numbered by 1. The inner moving plate has an index, marked "INDEX LVNAE" and with a moon symbol, and is engraved with a diagram of planetary aspects marked "ASPECTVS PLANETARVM." It is pierced to reveal on the first moveable representations of lunar phases and parts of inscriptions. A long central index arm extends beyond the limit of the base plate; around the central pivot is engraved "STELLA POLARIS PER QUAM VISVS PROIEC." The arm is marked "INDEX HORALOGII" and ":PLAVST VRSAM" and "DVAE PARILES PLAVSTRI POSTREMAE A POLARI STELLA IN RECTAM DVCTAE SOLIS INDICE AD DIEM POSITO NOCTUR HORAM OST." The handle on this side is engraved "ASTROLABII DOPSVM HORALOGIIOVE NOCTVRNALIS. OMNIA CONANDO DOCILIS SOLLERTIA VICIT."

The sundial side has a Regiomontanus-type altitude dial with 2 pinhole sight vanes and a three-element articulated arm for adjusting the point of suspension of the plumb-line (the line and weight are missing) on the triangular grid of latitude and zodiacal position. The zodiacal symbols are at the top, with each sign divided by three; the latitude scale is from 5 to 60, divided to 5, 5 to 65 subdivided to 1, numbered by 5. The grid is marked on one side "ZODIACI LATITVDINVM" and on the other "ZODIACI LATITVDINVM QUAE ET POLI ELEVATIO TAM NOTII QVAM BOREI." The hour lines are numbered both 1 to 12 "HORAE ANTE MERIDIANAE" and 12 to 1 "HORAE POMERIDIANAE." There is a solar declination scale to the right of the hour lines, marked with zodiac symbols, this scale and the mid-day hour line being marked "GENERALIS ZODIACVS MERIDIANVS." The midnight line is marked "MEDIVM NOCTIS SEPTENTRIO." Around the edge of the sundial side are two altitude scales to be used with the sights and the suspension point set to a position marked "QVADRANTVM CENTRVM." The outer is a scale of degrees marked "QVADRANS ASTRONOMICVS UNIVERSALIS." The inner is a geometrical quadrant or shadow-square scale marked "QVADRANS GEOMETRICVS" and "VMBRA VERSA" and "VMBRA RECTA."

This object, marked “F. Nr. E250/116,” is an unflown back-up for two rubidium frequency standards installed on NTS-1, the first of the Navigation Technology Satellites (NTS) launched to validate the key concepts and hardware for the Global Positioning System (GPS). NTS-1 (originally named Timation III) was built at the Naval Research Laboratory (NRL), Washington, D.C. It was launched in July 1974 and carried the first atomic clocks into space.

The compact rubidium frequency standard for NTS-1 is the Model FRK made by Efratom Elektronik, Munich, Germany. Gerhard Hübner and Ernst Jechart established the firm in 1971 and a year later supplied examples of the clock to NRL. Researchers had constructed relatively large laboratory rubidium frequency standards in the 1950s, and portable commercial versions were available by the mid1960s. But the FRK—weighing roughly three pounds and measuring about four inches on a side—was the smallest frequency standard of any type available in the early 1970s and attractive for space applications. NRL modified the commercial model for use in space, specifically to permit controlling its rate and frequency output from the ground.

Efratom established a branch in Irvine, California, in 1973 and manufactured compact rubidium frequency standards there for a variety of customers. The firm became a division of Ball Aerospace in 1982 and then part of Datum in 1995. Symmetricom acquired Datum in 2002.

Electromagnetic waves of very specific and consistent frequencies can induce atoms to fluctuate between two energy states, and by measuring that frequency we can determine the “tick” of an atomic clock. A second in a cesium clock, for example, is defined as 9,192,631,770.0 cycles of the frequency that causes the cesium atom to jump between those states. Different atoms “tick” at different rates – strontium atoms tick about 10,000 times faster than cesium atoms – but all atoms of a given element tick at the same rate, making atomic clocks much more consistent than clocks based on macroscopic objects such as pendulums or quartz crystals.

Steven Jefferts, physicist, National Institute of Standards and Technology.

This compact rubidium frequency standard is the commercial Model FRK, first made by Efratom Elektronik, Munich, Germany, and later by Efratom California in Irvine, Ca. Gerhard Hübner and Ernst Jechart established the firm in 1971 and a year later supplied examples of the clock to the Naval Research Laboratory (NRL), Washington, D.C., for inclusion on NTS-1, the first of the Navigation Technology Satellites (NTS) launched in 1974 to validate the key concepts and hardware for the Global Positioning System (GPS).

Relatively large rubidium frequency standards had been developed in the 1950s, but the FRK—weighing roughly three pounds and measuring about four inches on a side—was the smallest frequency standard of any type available.

Efratom established a branch in Irvine, California, in 1973 and manufactured compact rubidium frequency standards there for a variety of customers. The firm became a division of Ball Aerospace in 1982 and then part of Datum in 1995. Symmetricom acquired Datum in 2002.

Reference:

Carroll O. Alley et al., “Performance of the New Efratom Optically Pumped Rubidium Frequency Standards and Their Possible Application in Space Relativity Experiments,” Proc. of the 4th Ann. Precise Time and Time Interval (PTTI) Appl. and Planning Meeting, 1972, 29-40.

Brief description of an atomic clock

Electromagnetic waves of very specific and consistent frequencies can induce atoms to fluctuate between two energy states, and by measuring that frequency we can determine the “tick” of an atomic clock. A second in a cesium clock, for example, is defined as 9,192,631,770.0 cycles of the frequency that causes the cesium atom to jump between those states. Different atoms “tick” at different rates – strontium atoms tick about 10,000 times faster than cesium atoms – but all atoms of a given element tick at the same rate, making atomic clocks much more consistent than clocks based on macroscopic objects such as pendulums or quartz crystals.

Steven Jefferts, physicist, National Institute of Standards and Technology.

The 5071A Cesium Primary Frequency Standard was developed by Hewlett-Packard (HP) in the 1990’s. In 1999, an HP spinoff company, Agilent Technologies continued manufacturing the 5071A. In August 2005, Agilent sold the 5071A to Symmetricom, Inc., which then became the supplier. Finally, Microsemi Corporation acquired Symmetricom in October 2013. Microsemi continues to offer the 5071A

The 5071A is a source of extremely accurate and stable output frequencies. The accuracy of the 5071A is within a few parts in 10E12 of the internationally accepted definition of frequency. This accuracy is made more usable and practical by the 5071A’s excellent environmental stability.

How does the 5071A work?

The 5071A uses a fundamental property of the element cesium to define frequency. Inside the cesium beam tube assembly, an applied microwave signal causes energy-level transitions to occur in the cesium atoms. The microwave signal is synthesized from a 10 MHz Voltage-Controlled Crystal Oscillator (VCXO).

Patented Cesium II circuit and software technology detects departures of the microwave frequency from the cesium energy-level transition frequency and corrects them by tuning the VCXO to run precisely at the proper rational-fraction of the cesium frequency. The microprocessor (an integral part of this servo loop) performs the error determination and correction several times a second to ensure that the VCXO is always closely locked to the cesium transition frequency.

Many functions within the 5071A are under Cesium II software control. The software manages the initial warm-up and alignment, then continuously monitors the appropriate signals using this information to control all key operating parameters for optimum performance. Starting the 5071A merely requires connecting ac or dc power.

Electromagnetic waves of very specific and consistent frequencies can induce atoms to fluctuate between two energy states, and by measuring that frequency we can determine the “tick” of an atomic clock. A second in a cesium clock, for example, is defined as 9,192,631,770.0 cycles of the frequency that causes the cesium atom to jump between those states. Different atoms “tick” at different rates – strontium atoms tick about 10,000 times faster than cesium atoms – but all atoms of a given element tick at the same rate, making atomic clocks much more consistent than clocks based on macroscopic objects such as pendulums or quartz crystals.

Steven Jefferts, physicist, National Institute of Standards and Technology.

Johannes Van Ceulen made this clock in The Hague, Holland, in collaboration with Christiaan Huygens. Huygens (1629-1693) patented the design for the first practical pendulum clock in 1657.

In common with other so-called “Hague clocks,” which were made in several Dutch cities and by other clockmakers in Huygens’ time, this Van Ceulen clock has a single spring that drives both time and strike trains, a pendulum suspended between curved “cycloidal cheeks” (designed to correct the oscillation period of the pendulum for variations in its swing’s amplitude) and an ebonized fruitwood case reminiscent of classical architecture. The pediment of the case, with its gilt floral pattern, serves not only a decorative function, but also conceals the clock’s externally mounted bell. Also typical are the velvet-covered brass dial plate and the prominent figure of Chronos, or Father Time. The figure supports the chapter ring and rests on two signature plaques inscribed “Johannes Van/Ceulen Haghe.” The backplate is also marked “Johannes Van Ceulen/Fecit Haghe.” This clock has a two-day movement, verge and crown wheel escapement with crutch, silk thread suspension for the pendulum and count wheel striking. The alarm work is missing.

References:

1. Mahoney, Michael S. “Christian Huygens: The Measurement of Time and of Longitude at Sea,” in Studies on Christiaan Huygens, Edited by H.J.M. Bos et al. (Lisse: Swets, 1980), 234-270.

This instrument, made by John Roger Arnold about 1825, is a specialized timekeeper for finding longitude at sea. The chronometer was part of the James Arthur Collection at New York University, and the university donated a portion of the collection, including the chronometer, to the Smithsonian in 1984.

To find longitude at sea, a chronometer was set to the time of a place of known longitude, like Greenwich, England. That time, carried to a remote location, could be compared to local time. Because one hour of difference in time equals 15 degrees difference in longitude, the difference in time between the chronometer and local time would yield local longitude. The instruments require careful handling to keep precise time. Although the original box for this instrument has not survived, most chronometers are fitted in a wooden box in a gimbal to remain level and compensate for the movement of a ship at sea.

John Roger Arnold (1769-1843) learned watchmaking from his father, chronometer pioneer John Arnold, and Abraham Louis Breguet. The Arnolds were in business as Arnold & Son between 1787 and 1799, when the father died. In 1805 John Roger Arnold accepted the English Board of Longitude’s posthumous award to his father for improvements to the marine chronometer, which included simplifications that permitted others to undertake batch production of chronometers—a detached escapement, a helical balance spring and a temperature-compensated balance. The younger Arnold continued the business and between 1830 and 1840 took in partner Edward John Dent. In that decade, the firm made about 600 chronometers.

One of six ships of the U.S. Exploring Expedition, the Porpoise sailed around the world between 1838 and 1842 under the command of Lt. Cadwallader Ringgold. The four-year-long expedition, headed by Lt. Charles Wilkes, covered nearly 87,000 miles, including a full circumnavigation of the globe. Wilkes and his crew sighted Antarctica (proving its existence), charted hundreds of Pacific islands and surveyed the Columbia River in present-day Oregon.

This model was built in the 1980s by Dr. William Brown for an exhibition about the U.S. Exploring Expedition at the Smithsonian’s National Museum of Natural History.

The Seiko Quartz Astron 35 SQ was the first quartz wristwatch on the market. The first commercially available quartz watch went on sale in Tokyo on Christmas Day in 1969. With a limited production run of only about 100 pieces, these watches had analog dials and sold for 450,000 yen ($1250), roughly the same price as a Toyota Corolla. The watches were manufactured in Suwa City, Japan, by the firm Suwa Seikosha (now Seiko Epson) and were marketed by the parent company K. Hattori & Co., Ltd.

The case and band on the Smithsonian example are a reproduction of those that originally came with Seiko’s 1969 wristwatch. Inside is an original module that contains a hybrid circuit (a combination of circuits on a single substrate, an intermediate step between discrete circuits and integrated circuits), a quartz oscillator with a frequency of 8,192 cycles per second and a miniature stepping motor for moving the hands. Seiko claimed the new watches were accurate to within plus or minus 5 seconds a month, a minute a year.

At the time of the Astron’s introduction, Seiko produced more mechanical watches than any other firm in the world. But company officials had been experimenting with quartz timekeeping since the late 1950s. Beginning in 1959, a team of engineers, under Tsuneya Nakamura, started to develop a quartz wristwatch. Their first quartz timekeepers were battery-powered chronometers, one of which was used in the Olympic Games in Tokyo in 1964. By 1967, Seiko engineers had miniaturized the timekeeper to produce a wristwatch prototype. To develop manufacturing techniques required another two years.

The Astron was the first public indicator that the wristwatch was about to be completely reinvented, with all-new electronic components. When battery-driven quartz wristwatches like the Astron first hit the market, it seemed unlikely that the new-fangled gadgets would sell. But electronic watches won over the buying public in a few short years.

Reference:

Stephens, Carlene and Maggie Dennis. “Engineering Time: Inventing the Electronic Wristwatch,” British Journal for the History of Science 33 (2000): pp. 477-497.